1. Field of the Invention
The present invention relates to a thin-film magnetic head having at least an induction-type electromagnetic transducer for writing, and to a method of manufacturing such a thin-film magnetic head.
2. Description of the Related Art
The recording schemes for a magnetic recording/reproducing apparatus include a longitudinal magnetic recording scheme which employs the direction of signal magnetization along the surface of the recording medium (or in the longitudinal direction) and a vertical magnetic recording scheme which employs the direction of signal magnetization perpendicular to the surface of the recording medium. When compared with the longitudinal magnetic recording scheme, the vertical magnetic recording scheme is said to be less affected by the thermal fluctuation of a recording medium and therefore possible to implement a higher linear recording density.
In general, the thin-film magnetic head that employs the longitudinal magnetic recording scheme comprises: a medium facing surface (or air bearing surface) that faces toward a recording medium; a first and a second magnetic layer magnetically coupled to each other at a position farther from the medium facing surface and including magnetic pole portions that are opposed to each other and placed in regions of the magnetic layers closer to the medium facing surface, with a gap layer provided between the magnetic pole portions; and a thin-film coil at least a part of which is placed between the first and the second magnetic layers and insulated from the first and second magnetic layers.
On the other hand, examples of the thin-film magnetic head that employs the vertical magnetic recording scheme include a ring head having the same structure as that of the thin-film magnetic head that employs the longitudinal magnetic recording scheme, and a single magnetic pole head for applying a magnetic field in a direction perpendicular to the surface of the recording medium with one main magnetic pole. Generally, for the single magnetic pole head, used as a recording medium is a two-layer medium that has a soft magnetic layer and a magnetic recording layer stacked on a substrate.
It has been desired to reduce the write track width of a recording medium to cope with a recent increase in recording density. Accordingly, it has also been desired to reduce the width of the main magnetic pole. However, as described below, there have been two problems which make it difficult to reduce the width of the main magnetic pole.
A first problem is that it is difficult to pattern the main magnetic pole with high accuracy, for example, in such a manner that the main magnetic pole is made to have a width of 0.5 xcexcm or less. The main magnetic pole is formed by electroplating (frame plating), for example, using a resist frame that is formed by photolithography. Conventionally, the main magnetic pole is formed on a hill-like raised portion of an insulating layer that covers the coil, and therefore, the resist frame is formed on the insulating layer having great differences in height of irregularities. In this case, it is difficult to form the resist to have a uniform thickness, and accordingly it is difficult to pattern the resist frame with accuracy. This in turn makes it difficult to pattern the main magnetic pole with high accuracy.
A second problem is that a reduced width of the main magnetic pole makes it difficult to efficiently introduce a magnetic flux to the tip of the main magnetic pole, thereby weakening the magnetic field generated from the tip of the main magnetic pole in the medium facing surface.
To overcome these problems, thin-film magnetic heads for use with the longitudinal magnetic recording scheme often employ a structure in which one of magnetic layers is divided into a magnetic pole portion to be exposed in the medium facing surface and a yoke portion for introducing a magnetic flux into the magnetic pole portion.
Accordingly, it has been proposed for the single magnetic pole heads for use with the vertical magnetic recording scheme, too, to employ such a structure in which the main magnetic pole is divided into a magnetic pole portion to be exposed in the medium facing surface and a yoke portion for introducing a magnetic flux into the magnetic pole portion. This structure makes it possible to efficiently introduce the magnetic flux to the tip of the main magnetic pole by making the saturated magnetic flux density of the magnetic pole portion greater than that of the yoke portion, and to reduce the width of the magnetic pole portion.
For conventional thin-film magnetic heads for use with the longitudinal magnetic recording scheme, where they are configured such that one magnetic layer is divided into the magnetic pole portion and the yoke portion, in many cases the yoke portion is joined to only one of surfaces of the magnetic pole portion that is farther from the gap portion. However, this structure provides only a small area of the interface between the magnetic pole portion and the yoke portion, which causes the magnetic flux to be readily saturated at the interface. Therefore, this structure cannot meet the recent demand for enhancing magnetic fields for writing operations. To overcome this, thin-film magnetic heads having the following structure have been proposed in Published Unexamined Japanese Patent Application (KOKAI) No. Hei 11-102506, No. 2000-57522, No. 2000-67413 and No. 2000-149218. That is, the heads have a structure in which the yoke portion is joined to the magnetic pole portion not only at the surface of the magnetic pole portion farther from the gap portion but also at both side surfaces of the magnetic pole portion and at a surface of the magnetic pole portion farther from the medium facing surface.
For the single magnetic pole heads for use with the vertical magnetic recording scheme, where they are configured such that the main magnetic pole is divided into the magnetic pole portion and the yoke portion, it is conceivable to employ the structure in which the yoke portion is joined to the magnetic pole portion not only at the surface of the magnetic pole portion farther from the gap portion but also at the side surfaces of the magnetic pole portion and the surface of the magnetic pole portion farther from the medium facing surface, like the aforementioned heads for use with the longitudinal magnetic recording scheme.
For a head for use with the vertical magnetic recording scheme, it is important to increase the intensity of magnetic field in the direction perpendicular to the surface of the recording medium. However, even if the aforementioned structure is employed for the head for use with the vertical magnetic recording scheme, it is impossible to increase the intensity of the magnetic field in the direction perpendicular to the recording medium, because the areas of the interfaces between the yoke portion and the magnetic pole portion available at the surface of the magnetic pole portion farther from the medium facing surface and at the side surfaces of the magnetic pole portion are relatively small as compared with the area of the interface at the surface of the magnetic pole portion farther from the gap portion.
It is therefore an object of the invention to provide a thin-film magnetic head which allows the magnetic pole portion to produce a greater magnetic field perpendicular to the surface of a recording medium and has an improved recording density, and a method of manufacturing such a thin-film magnetic head.
A thin-film magnetic head of the invention comprises: a medium facing surface that faces toward a recording medium; a first magnetic layer and a second magnetic layer that are magnetically coupled to each other at a distance from the medium facing surface, and include magnetic pole portions disposed to oppose to each other with a predetermined spacing interposed therebetween along the traveling direction of the recording medium; a gap layer made of a non-magnetic material and provided between the first and second magnetic layers; and a thin-film coil at least part of which is disposed between the first and second magnetic layers and insulated from the first and second magnetic layers.
In the thin-film magnetic head, the second magnetic layer has: a pole portion layer including the magnetic pole portion, the width of the pole portion layer measured in the medium facing surface defining a track width; and a yoke portion layer for magnetically connecting the pole portion layer and the first magnetic layer to each other.
The yoke portion layer is magnetically connected to the pole portion layer at least in part of: an end surface of the pole portion layer farther from the medium facing surface; and side surfaces of the pole portion layer in the width direction.
The pole portion layer has a connection surface that is magnetically connected to the yoke portion layer. The connection surface is at least part of: the end surface of the pole portion layer farther from the medium facing surface; and the side surfaces of the pole portion layer in the width direction. At least part of the connection surface is inclined relative to the direction perpendicular to a surface of the pole portion layer that faces the gap layer.
In the thin-film magnetic head of the invention, as described above, at least part of the connection surface of the pole portion layer is inclined relative to the direction perpendicular to the surface of the pole portion layer that faces the gap layer. This makes the connection surface larger in area as compared with the case where the connection surface is perpendicular to the surface of the pole portion layer that faces the gap layer. The magnetic flux is therefore efficiently introduced from the yoke portion layer into the pole portion layer through the connection surface. As a result, it is possible to increase the intensity of the magnetic field generated from the magnetic pole portion in the direction perpendicular to the surface of the recording medium.
In the thin-film magnetic head of the invention, the at least part of the connection surface may be inclined at an angle of more than 90xc2x0 relative to the surface of the pole portion layer that faces the gap layer.
In the thin-film magnetic head of the invention, in a cross section containing the at least part of the connection surface, the yoke portion layer may be greater than the pole portion layer in thickness.
In the thin-film magnetic head of the invention, the yoke portion layer may be magnetically connected to the pole portion layer further at a surface of the pole portion layer farther from the gap layer. In this case, the thin-film magnetic head may further comprise a non-magnetic layer that touches the surface of the pole portion layer farther from the gap layer, and, the yoke portion layer may be adjacent to the surface of the pole portion layer farther from gap layer via the non-magnetic layer, and magnetically connected to the pole portion layer via the non-magnetic layer.
The thin-film magnetic head of the invention may further comprise a non-magnetic layer that touches the entirety of the surface of the pole portion layer farther from the gap layer. In this case, the vicinity of a part of a surface of the yoke portion layer farther from the gap layer, the part being magnetically connected to the pole portion layer at least in part of: the end surface of the pole portion layer farther from the medium facing surface; and the side surfaces of the pole portion layer in the width direction, may be flattened together with a surface of the non-magnetic layer farther from the gap layer.
In the thin-film magnetic head of the invention, the yoke portion layer may be magnetically connected to the pole portion layer further at the surface of the pole portion layer that faces the gap layer.
In the thin-film magnetic head of the invention, the pole portion layer may have a saturated magnetic flux density equal to or greater than that of the yoke portion layer.
The thin-film magnetic head of the invention may further comprise a magnetoresistive element as a read element.
The thin-film magnetic head of the invention may be employed for a vertical magnetic recording scheme.
The invention provides a method of manufacturing a thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a first magnetic layer and a second magnetic layer that are magnetically coupled to each other at a distance from the medium facing surface, and include magnetic pole portions disposed to oppose to each other with a predetermined spacing interposed therebetween along the traveling direction of the recording medium; a gap layer made of a non-magnetic material and provided between the first and second magnetic layers; and a thin-film coil at least a part of which is disposed between the first and second magnetic layers and insulated from the first and second magnetic layers, wherein the second magnetic layer has: a pole portion layer including the magnetic pole portion, the width of the pole portion layer measured in the medium facing surface defining a track width; and a yoke portion layer for magnetically connecting the pole portion layer and the first magnetic layer to each other.
The method comprises the steps of: forming the first magnetic layer; forming the gap layer; forming the thin-film coil; and forming the second magnetic layer having the pole portion layer and the yoke portion layer.
The second magnetic layer is formed such that the yoke portion layer is magnetically connected to the pole portion layer at least in part of: an end surface of the pole portion layer farther from the medium facing surface; and side surfaces of the pole portion layer in the width direction, such that the pole portion layer has a connection surface that is magnetically connected to the yoke portion layer, the connection surface being at least part of the end surface of the pole portion layer farther from the medium facing surface and the side surfaces of the pole portion layer in the width direction, and such that at least part of the connection surface is inclined relative to the direction perpendicular to the surface of the pole portion layer that faces the gap layer.
According to the method of manufacturing the thin-film magnetic head of the invention, as described above, at least part of the connection surface of the pole portion layer is inclined relative to the direction perpendicular to the surface of the pole portion layer that faces the gap layer. This makes the connection surface larger in area as compared with the case where the connection surface is perpendicular to the surface of the pole portion layer that faces the gap layer. The magnetic flux is therefore efficiently introduced from the yoke portion layer into the pole portion layer through the connection surface. As a result, it is possible to increase the intensity of the magnetic field generated from the magnetic pole portion in the direction perpendicular to the surface of the recording medium.
In the method of the invention, the at least part of the connection surface may be inclined at an angle of more than 90xc2x0 relative to the surface of the pole portion layer that faces the gap layer.
In the method of the invention, in a cross section containing the at least part of the connection surface, the yoke portion layer may be greater than the pole portion layer in thickness.
In the method of the invention, the yoke portion layer may be magnetically connected to the pole portion layer further at the surface of the pole portion layer farther from the gap layer. In this case, the method of the invention may further comprise the step of forming a non-magnetic layer that touches the surface of the pole portion layer farther from the gap layer, and, the yoke portion layer may be adjacent to the surface of the pole portion layer farther from the gap layer via the non-magnetic layer, and magnetically connected to the pole portion layer via the non-magnetic layer.
The method of the invention may further comprise the step of forming a non-magnetic layer that touches the surface of the pole portion layer farther from the gap layer. In this case, the step of forming the second magnetic layer may include, after the step of forming the non-magnetic layer, the steps of: forming at least a part of the yoke portion layer to be magnetically connected to the pole portion layer; forming a protective layer to cover the non-magnetic layer and the yoke portion layer; and polishing the protective layer to expose the non-magnetic layer, and then flattening the vicinity of a part of the surface of the yoke portion layer farther from the gap layer, the part being magnetically connected to the pole portion layer at least in part of: the end surface of the pole portion layer farther from the medium facing surface; and the side surfaces of the pole portion layer in the width direction, together with the surface of the non-magnetic layer farther from the gap layer.
In the method of the invention, the yoke portion layer may be magnetically connected to the pole portion layer further at the surface of the pole portion layer that faces the gap layer.
In the method of the invention, the pole portion layer may have a saturated magnetic flux density equal to or greater than that of the yoke portion layer.
Other and further objects, features and advantages of the invention will appear more fully from the following description.